Indicator for electrical measuring instruments.



- PATENTED AUG.13, 1907. I. G. SIMPSON. & w. M. PRICE.

INDICATOR FOR ELECTRICAL MEASURING INSTRUMENTS.

nruonmn FILED Nil-29,1904.

UNITED STATES PATENT oFFIoE.

FREDERICK GRANT SIMPSON AND WILLIAM MOUTELIUS PRICE, OF SEATTLE, WASHINGTON.

INDICATOR FOR ELECTRICAL MEASURING INSTRUMENTS.

To all whom it may concern:

Be it known that we, FREDERICK GRANT SIMPSON and WILLIAM Mourntrus PRICE, citizens of the United States, both residing at Seattle, in the county of King and State of Washington, have invented a new and useful Indicator for Electrical Measuring Instruments, of which the following is aspecification.

Our invention relates to indicators which may be installed with or attached to instruments for measuring direct, pulsating or alternating currents, and its purpose is to prevent tapping'oi the circuits by maliciouslydisposed persons, to detect defective installation or wiring, or other diversion irom such measuring instruments of the currents designed to pass through them.

The invention comprehends more particularly an armature controlled by a magnetically-balanced electrdmagnet Whose exciting current is developed in vari ous ways, depending upon the nature of the current being measured and of the connections of the instrument.

. In the accompanying diagrammatic drawings, Figure 1 illustrates our invention as applied to a twoavire, continuous-current system; Fig. 2, shows its application to an Edison three-wire 6r convertible twoto three-wire, continuous-current system; 3, shows its application to a two-wire system for either pulsating or alternating currents and Fig. 4, shows its application to an Edison three-wire, or convertible twoto three-wire,

system or pulsating or alternating currents.

Similar reference character indicate like parts, in each of the figures.

,In Fig. l, the wires 2, 3, represent a portion of the mains before they enter the measuring instrument. The main Zis carried in a coil 5 around one core 7 of an clcctronnagnet and passes thence to the measuring instrument, to which it is connected in any manner necessitated by the type-0t instrument used,-and thence to line. The wire 3 forms a coil 6 around the other core 8 oi the magiiet, the direction of the coil-winding being such that the polarity of the magnetism induccgl in the core 8 is opposed to that of the core 7; these cores being magnetically connected by a yoke y; The result of this manner of winding is that the armature a is not at tractcd by the cores 7, 8, until the magnetic balance is destroyed by some disturbance in the circuit. This disturbing element may be a conductor connecting any two points of either of the mains 2, 3, on opposite sides of the measuring instrument .10, so as to form a shunt around it, or it may be leakage due to defective installation or damaged insulation. The effect of any such connection or defect is to vary the magnetism of the core embraced by the coil so shunted or included in the doiective portion of the circuit, destroy the original magnetic balance and attract the armature It; thus actuating any indicating device controlled by the armature.

In Fig. 2, the wires 2, 3' 4, represent, as before, portions of the mains before they enter the measuring Specification of Letters Iatent. Application filed April 29,1904. Serial No. 205,506.

(owner 1', thence connected to the measuring inslru Patented ug. 13, 1907.

current therein is at all times equal to the difference 0f the currents then flowing in the mains 2 and 4, and is always flowing in the direction of the lesser current flowing at that instant in either of the other mains. This current in the neutral main, flowing through coil 6, induces a polarity in the core 8 which, together with that induced by the coil which is at that instant carrying the lesser current in the outside main, balances the effect of the polarity induced by the flow in. the coil carrying the larger current; and the armature, as before, remains at rest. But this magnetic balance may be destroyed by any of the line disturbances described in connection with Fig. 1.

In cases where the main 3 carries the sum of the currents of the mains 2 and 4*, the current in the coil 6 is at any instant equal and opposite to the sum oi the currents in the coils 5 and 9, and the mag; tic balance of the cores and yoke is still maintained.

In Fig. 3, the wires 2 and 3 represent those portions of mains carrying pulsating or alternating currents, before said mains enter the measuring instrument. In this case, the main 2 is carried through the primary ll of atransformer t, thence through the primary 15 of the transformer t, and thence as above described. The main 3 is carried through the primary 13 of a transformer thence connected to the measuring instrument in any desired manner, and thence carried to line. The secondaries l2 and 140i the transl'ori lCl'S L and are so connected through their respective coils 5 and (5" that the currents in these coils are equal and opposite to each other, thus establishing a. magnetic balance in the cores 7 and 8 Again. any of the line disturbances above described will destroy this balance and actuate the arm-at ure (1.

in Fig. i, is rcprcsmucd tho modc of wiring the indicator in a lhrccaviic. or convertible IWO to tln'eewire system carrying pnlsat ing or alternui ing currents. The wires 2, 3 and =l" represent the mains. as described above in connection with Fig. 2. In this case the wire 2 is carried through the primary ll ol the translormor t ihencc llil'ml ll the rinnu' 15 oi the transa l ment, as desired, and thence carried to line. \\'ire 3" is carried through one oi'the primary coils Ill" ol the transformer thence ponnected to the measuring instrinncnt. as dcsircd. ai'ld thorn-o carried lo line Wire 4 is carried through the other coil 13" of lhe transformer t". thence to the measuring instruumnt and lhcncc to line.

In the transformers t and t Figs. 3 ands, the coils 1.6, 16 are composed of fine wire, so wound as to produce a high impedance, and connected to the mains 2",

3" and 2, 4 respectively. The current flowing inthese coils due to the impressed electro-motive force, will induce a counter electro-motive force in the coils 1.5, 15". The coils 15, 15 are of course Wire and become shortcircuited secondaries to the coils 16, 16, when a shunt is connected to either 2 or 2, in the manncr'dcscrihcd with reference to Fig. 1, thereby permitting a current of maximum intensity to flow-through 15 or 15 and through the shunt in a direction opposite to that induced bythe impressed electro-motive iorce, thereby inducing currents in the seoondariesl2 or 12 in the same direction as that flowing at the same instant in the secondaries 13 or 13, and destroying the magnetic balance in the armaturecontrolling cores.

Our object in inserting the transformers i, t in the systems shown in Figs. 3 and 4, is to provide an additional means of destroying the magnetic balance in the indicator cores, and to guard'against the bridging of the primary circuits in both the transformers. as t, t, at the same instant.

In cases where the main 3 carries the sum of the currents flowing in the mains 2, 4, the current flow through the primary 13 of the transl'ormer'l is equal and opposite to the current flow in the primary 13 oi tirely within thecasing of themeter in connection with which it is used, or the connections. between the indicator' and meter so protected that-it is impossible to make an electrical connectionwith the conductors between the indicator and the meter or between any of the parts of the indicator itself.

The operation is as follows: Any attempted-shunt in any of the branchesZ, 3, 2', 3} or 4 will, by varying the resistance of that bran'clnoverthrow the magnetic bal'-" ance of the. device and operate the indicator. In the modification. of Fig. 3, for example, not only would it be practically impossible to simultaneously cut out both branches of the main circuit around the indicator and meter by shunts of such low resistance as to render the transformers inert; but, if it were accomplished, there would be setup a current in the secondary 16 of transformer t which would induce a current in coils l5, 11

and 12,1sufiicient to actuate the indicator. It primary having its coils in said secondary circuitfand an :lIlXlll 13 ol'transl'ornu-r 1" were at that instant absolutely inert. its secondary 14 would furnish no current Io oppose that 01' the coil 12; as during the normal action of the transformers. 11'. on the oiherhand, a slight current should. at that instant, be flowing through lid/it would induce in 14 a current which would reinforce that oi secondary 12, instead 01' opposing it, and the indicator would still be actuated. The operation of the modification oi Fig. 4 is similar to that justexplained in systems carrying alternating currents the magnet cores may be laminated, if desired. to prevent heating.

The skilled electrician will be able to modify in various ways the circuits above-described, without departing from the spirit of our invention; nco

What we claim is:

1. The combination-oi a normally closed electrical circuit. a measuring instrument having members connected in series and in shunt in said circuit, a eries-\\'ound. magnetically-archerted indicator having a l-opcruliu; armature and operiatively connected with said circuit. and magnetizing means for said indicator, said means lJLlIILf so constructed and arranged as to release said indicator armature when said measuring instrument is receiving in normal current; substantially as described.

In an indicating device for clec ical measuring in- -struments, a primary circuitcontaining :1 measuring in strument and a plurality 01' transformers having their secondaries connected ench.to balance the others, an electro-magnet having its winding interposed in said secondary circuit and an indicating armature adapted to be actuuted by the unbalancing of the currents flowing in the respective leads of the primary circuit: substantially as described.

3. In an indicating device for electrical mmisuril struments, a primary circuit comprising the measu nu instrument and a plurality of transformerprlmarics. said transformers havim, their secondaries connected each to balance the others under normal cm'rentcon(litions in the primaries, an electro-magnet having its winding interposed in said secondary circuit, and an indicating armature adapted to be actuated by the core of said t5l0LZlZl'()-lll;l;ll(!1' when the cui-rent conditions in the respective leads of said primary circuit become, abnormal: substantially as described;

4. In'an indicator for electrical measuring instruments. :3. main circuit, a transformer in each brunch u! said circult, said transformers having their secondarit connected eaehfio balance the effect of the others, an eIectro-m :u'y transformer having its primary in one branch of the main circuit and its secondary connected to a plurality of \branches of the main circuit; substantially as described.

FREDERICK GRANT SIMPSON. WILLIAM MOUTIGLIIIS HUGE. Witnesses:

II. B. Hora, 1111mm 0. GILL. 

